<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <ImageView
         android:id="@+id/pla"
         android:layout_width="match_parent"
         android:layout_height="match_parent" />
    <Button
         android:id="@+id/btn"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="next one"/>
</android.support.constraint.ConstraintLayout>